Along with the trend in recent years toward compactness and high integration of semiconductor devices, the light sources for the fine working thereof are also under a trend of gradual shift to shorter wavelength ones from traditional UV light having a long wavelength such as the g-line (436 nm), the i-line (365 nm) and the like to the KrF excimer laser (248 nm) capable of forming a resist pattern of higher pattern resolution, leading to the current ArF excimer laser (193 nm) and further electron beams such as EB, EUV and the like shifter as a major current while developments of the process and resist materials are under progress at a high pace in order to comply with these short-wavelength light sources.
Conventional photoresists are required to have: for instance, improved sensitivity, pattern resolution, heat resistance, focusing depth latitude, cross sectional profile of a resist pattern, aging stability resulting in the deterioration of the shape of the resist pattern due to contamination with amine and the like in a period between light exposure and post-exposure baking (PEB) and substrate dependency which changes are caused in the cross sectional profile of the resist pattern depending on various coating films on the silicon wafer such as insulating films including silicon nitride (SiN) films, semiconductor films including polycrystalline silicon (poly-Si) films and metallic films including titanium nitride (TiN) films. These requirements have been solved to some extent, but a defect which is a particularly important issue has problems remaining unsolved.
The defect means a mismatch between a resist pattern and the photomask pattern, which is detected when a resist pattern after having been developed is examined with a surface defect observation instrument, for instance, the mismatch like a difference between shapes of the patterns, occurrence of scums and contaminants, irregular coloring and coalescence between the patterns. The yield of the semiconductor devices decreases as the number of defects increases so that, even though the resist has the adequate resist characteristics as described above, defects make it difficult for the semiconductor devices to be effectively mass produced, while the problems thereof remain unsolved.
Besides, in recent years, it has become essential to solve the problems including resist pattern falling as a particular problem in the formation of resist patterns under the trends toward ultra-fineness and high aspect ratio. The resist pattern falling occurs under a surface tension which takes place in the step of drying of a rinse solution.
In addition, the aforementioned lithographic cleaning solution for effects of decreasing defects and suppressing resist pattern falling as the objects is further required to be capable of non-uniformity of the pattern width (LWR) and fine ruggedness appearing on the side walls of the pattern (LEW) and to be capable of improving the size changes in the undesirable variations in the dimensions of the resist pattern per se. The requirement is for a lithographic cleaning solution capable of satisfying all of these necessary characteristics.
Incidentally, in order to improve the properties of the thus obtained resist pattern, the cleaning solutions for lithography currently under use in the rinse steps to follow the development treatment include mixtures of isopropyl alcohol and water or isopropyl alcohol and Freon (JP5-299336A), aqueous solutions containing an anionic surfactant (JP2002-323773A), organic treatment solutions containing fluorine (JP2003-178943A and JP2003-178944A), a nonionic surfactant-containing rinse solution for lithography having water and ethyleneoxy group and free from any fluorine atom (JP2004-184648A) and others as the known ones.
However, mixtures of isopropyl alcohol and water or Freon are not so effective as desirable in the defect-decreasing effects. The aqueous solutions containing a surfactant are not also suitable for preventing pattern falling and decreasing the defects since the concentration of surfactant therein should be low in order to suppress the dissolution of the resinous ingredient in the photoresist while, such a limited concentration of the surfactant leads to the increased surface tension as a disadvantage.
On the other hand, there is a proposal for decreasing the defects to improve the positive-working resist composition used for the formation of patterns (JP2002-148816A) but this measure is not practicable because modification of the components of the photoresist composition must be preceded by a modification of the process per se for the supply of the components of the photoresist composition.
Further, a method is known (JP2001-23893A) for coating, in the course of resist-pattern forming, with a defect treating agent having a hydrophobic group and a hydrophilic group or, namely, with a surfactant but this method has shortages that the top portion of the resist pattern is rounded to degrade the orthogonality of the cross section and, in addition, film thickness reduction of the resist layer is caused by this treatment. Besides, a developer solution is usually supplied through a collective pipeline throughout the development treatment so that, in a semiconductor manufacturing plant wherein various resists should be used, it is necessary to exchange the treatment agent to be used corresponding to the respective resist, and to clean the device and the pipeline after each run. Consequently, this method is unsuitable.
Furthermore, there are known a method for decreasing the defects in the developing step of photolithography by using a developer solution containing a nonionic surfactant and an organic base free from metallic ions as a principal ingredient (JP2001-159824A) and a method for decreasing the defects by conducting a treatment prior to the post-exposure baking treatment by using an aqueous solution of pH 3.5 or lower containing a low-volatile aromatic sulfonic acid and having a molecular weight of at least 200 (JP2002-323774A) but no satisfactory results can still be reached.
On the other hand, a method of using a composition of a rinsing agent containing a nitrogen-containing compound with a molecular weight of 45 to 10000, which has an amino group or an imino group, and a hydrocarbon group with 1 to 20 carbon atoms in the molecule, so as to inhibit falling and damage on a resist pattern occurring in a rinsing step and a drying step (JP11-295902A) is also known, but the defect-decreasing effect mentioned above can not be obtained with such a composition of a rinsing agent. Besides, a rinse solution containing an ethylene oxide-based or propylene oxide-based activator (JP2004-184648A) is known, but the aforementioned effects of decreasing defects and inhibiting pattern falling can not be obtained because the hydrophilic group has weak interaction with water.